Replacement of the central Mg in chlorophylls by Ni opens an ultrafast (tens of femtoseconds time range) radiationless de-excitation path, while the principal ground-state absorption and coordination properties of the pigment are retained. A method has been developed for substituting the native bacteriochlorophyll a by Ni-bacteriochlorophyll a ([Ni]-BChl)… (More)

We investigated the dependence on solvents of optical absorption and emission of the bacteriochlorophyll a-serine (BChl-ser), a water soluble bacteriochlorophyll (BChl) derivative. Comparison between the experimental data and those collected for BChl in nonaqueous solvents shows that only a minor interaction takes place between serine and the macrocycle's… (More)

The excited-state and lasing properties of 20-chloro-chlorophyll a in ether solution were compared to those of chlorophyll a. Desactivation parameters and cross-sections were obtained from non-linear absorption spectroscopy in combination with a phys-ice-mathematical methods package. The Cl substituent at C-20 (I) increases both intersystem crossing and… (More)

By means of fluorescence spectroscopy and nonlinear absorption experiments, excited-state processes of the modified pigments [3-acetyl]-chlorophylla, [3 1-OH]-bacteriochlorophyl! a and [3-vinyl]-bacteriochlorophyll a were investigated and compared with those of chlorophyll a and bacteriochlorophyll a. I. Introduction because the structural differences… (More)